WHEN WILLIE Martinez began fixing cars in a dingy garage in Kensington last year, it didn't take long to meet his new neighbors - trash-dumpers who chucked everything from construction debris to unwanted furniture in the overgrown, abandoned lot, and hookers and addicts who used the detritus to hide their illicit activity.

"I tried to put a gate up there, but everybody says they own it," said Martinez, who also has a towing business. "Then I'd kick [addicts and prostitutes] out, but they'd break the windows of the cars I had parked here."

Now, it seems that a serial killer has succeeded where Martinez and legions of community activists have not: In lots where the psychotic Kensington Strangler has struck, and in other neglected properties, the blight is beginning to disappear, as residents and city workers partner to erase places where the Strangler could attack again.

"It's a shame it took this to clean it up," Martinez said of the lot, adjacent to his garage, where the killer's first-known victim, Elaine Goldberg, was found Nov. 3.

In a neighborhood where abandoned properties number in the hundreds, blight has long been a lure for lawbreakers. Kensington's trashy lots and vacant homes prove irresistible spots for dealers to stash drugs, hookers to turn tricks and addicts to shoot up.

But since early December, 64 vacant lots have been swept clean in Kensington under the mayor's Office of Neighborhood Services vacant-lot program, said Thomas Conway, the office's deputy managing director. The December cleanup in Kensington was scheduled long before the Strangler's first known victim was discovered. But workers tackled more lots than originally planned, to help authorities avert more strangulations, Conway said.

Some worry that the spruce-up could be short-lived.

The city's Community LandCare program, under which 2,600 neglected lots citywide have been swept clean since its 2003 inception, lost funding under the city's recent budget cuts, said Bob Grossmann, director of the Pennsylvania Horticultural Society's Philadelphia Green, which runs Community LandCare.

In Kensington, that meant the end of a $70,000 annual grant to clear trash, build fences and plant grass on abandoned lots.

The grant and other community efforts helped foster "an amazing renaissance of the community," said Sandy Salzman, executive director of the New Kensington Community Development Corp. "But we're very concerned that this could all be lost. Blight is bad, bad, bad."

The three lots where the Strangler struck illustrate ways in which properties can become blighted:

* The block of Ruth Street near Hart Lane where Goldberg, 21, a nursing student who'd struggled with drug addiction, was found in underbrush, is dotted with vacant lots and houses. Property records list the owner as Philip DiIenno, who's also listed as the owner of five other vacant, neglected parcels on that block.

Such bulk ownership is common in Kensington, said A.J. Thomson, a longtime Kensington resident and board member of the New Kensington Community Development Corp. Investors who picked up properties cheap either are waiting for the market to rebound to sell or can't secure a buyer, Thomson said. Because the city has too few code-enforcement officers to police more than 40,000 vacant lots and buildings citywide, owners have little incentive to maintain them, Thomson said.

DiIenno's neglected stretch of land was a popular draw for addicts, prostitutes and other derelicts, neighbors said. After Goldberg's slaying, a city inspector declared the property a public nuisance and ordered DiIenno to clean it, Conway said. After two weeks with no improvements, city workers cleared it, and the city will bill DiIenno for the cleanup cost, Conway said.

The Daily News couldn't locate DiIenno for comment.

* Cumberland Street near Jasper, where Nicole Piacentini, 35, was killed Nov. 13, has more blighted, vacant properties than occupied ones. The crumbling, abandoned home behind which her body was found is owned by Grace S. Park, according to city records.

But Park is dead, according to public records.

"That's a very big issue: folks die off, and there is no next-of-kin," Conway said. "Then you have just a piece of land that's sitting in the city of Philadelphia: We don't want it, because then we're responsible for it. But then it just sits there [decaying]."

Park's crumbling rowhouse won't decay much longer.

The property "qualifies for immediate demolition, and the city is pursuing that," said City Councilwoman Maria Quinones-Sanchez, whose district neighbors that area.

* The place where Casey Mahoney, 27, was strangled Dec. 5 is a wide, weedy swath of land between Tusculum Street and railroad tracks that cut under Front Street. Of the three strangling scenes, it's the only one that hasn't been cleaned up.

Property records show that it's owned by the Philadelphia-Reading Railroad Division, a company that no longer exists.

Try figuring out who owns it now.

"That's not ours," CSX spokesman Bob Sullivan said.

"I don't know if it's our property or not, but even if it were our property, I don't know that it's something we could confirm or deny," Conrail spokesman John Enright said.

The property also does not belong to SEPTA, spokesman Andrew Busch said.

"This is a major problem for our neighborhoods," said the New Kensington Community Development Corp.'s Salzman. "The community is really fed up with how [the railroad companies] are not taking care of their rights-of-way."

Conrail's Enright insisted that maintaining rights-of-way is a priority, both for the safety of train personnel and the public. Still, keeping determined lawbreakers at bay can prove problematic, he acknowledged.

"When you have miles and miles of rail lines, you can't be there every hundred feet, making sure no one is trespassing," Enright said.

Addicts and others still flock to the right-of-way where Mahoney was strangled, even with the police tape still fluttering in the wind, crumbling concrete barriers and chain-link fences blocking access and snow obscuring a path cut through the brush. One recent weekday morning, fresh hypodermic needles littered the snow and a man ducked into the brush, apparently to urinate.

The Strangler's other crime scenes offered similar evidence last week that mere cleanups won't keep troublemakers away.

On Ruth Street, as a jittery addict paced the sidewalk down the block, Martinez predicted that it wouldn't be long before the dealers, addicts, hookers and johns return.

"You clean it up, it gets trashy the next week, because people in this neighborhood don't care about nothing: They're the ones coming and dumping the trash," Martinez said. "And a crackhead is always going to try to get high, no matter where they go."